Introduction Occipitocervical instability may be traumatic occipitocervical dislocation severe injury and patients rarely survive most patients die of brainstem destruction acquired occipitocervical instability may be seen in patients with Down's syndrome occipital condyle hypoplasia results in limited AOJ motion and basilar invagination Epidemiology traumatic incidence ~15-30% of cervical spine injuries occur at the occipitocervical junction prevalence identified in 19% fatal cervical injuries acquired most frequently seen in Down syndrome population usually asymptomatic and identified in screen for surgery or special olympic participation Pathophysiology traumatic mechanism of injury high-energy trauma translation or distraction injuries that destabilize the occipitocervical junction pathoanatomy head most often displaces anteriorly acquired pathoanatomy due to bony dysplasia or ligament and soft-tissue laxity Associated conditions atlantoaxial instability also seen in Down syndrome patients neurologic deficits vertebral or carotid artery injuries Down Syndrome Classification Traynelis Classification (direction of displacement) Type I Anterior occiput dislocation Type II Longitudinal dislocation Type III Posterior occiput dislocation Harbourview Classification System (degree of instability) Stage I Minimal or non-displaced, unilateral injury to craniocervical ligaments Stable Stage II Minimally displaced, but MRI demonstrates significant soft-tissue injuries. Stability may be based on traction test Stable or Unstable Stage III Gross craniocervical misaligment (BAI or BDI > 2mm beyond normal limits) Unstable Imaging Radiographs recommended views AP, lateral and odontoid views findings low sensitivity in detecting injury (57%) measurements used to diagnosis occipitocervical dislocation Powers ratio = C-D/A-B C-D: distance from basion to posterior arch A-B: distance from anterior arch to opisthion significance ratio ~ 1 is normal if > 1.0 concern for anterior dislocation ratio < 1.0 raises concern for posterior atlanto-occipital dislocation odontoid fractures ring of atlas fractures Harris rule of 12 basion-dens interval or basion-posterior axial interval >12mm suggest occipitocervical dissociation CT indications considered gold standard for osseous injuries of the spine views midsaggital CT reconstruction MRI indications suspected ligamentous injury with preserved alignment or occult injury neurological deficits Treatment Nonoperative provisional stabilization while avoiding traction indications traumatic instability with distraction of the occipitoatlantal joint techniques halo vest tongs prolonged cervical orthosis is not recommended due to poor stabilization of the AOJ outcomes use of traction should be avoided in most cases traction may be considered in stage 2 injuries when MRI demonstates soft-tissue injury with perserved aligment Operative posterior occipitocervical fusion (C0 - C2 or lower) indications most traumatic cases require stabilization acquired cases when evidence of myelpathy or significant symptomatic neck pain invagination and atlanto-axial impaction secondary to inflammatory arthropathy (e.g., rheumatoid arthritis) tumor Technique Posterior occipitocervical fusion approach midline posterior approach to base of skull instrumentation rigid occipitocervical screw-rod or plate construct aim for 3 unicortical occipital screws on each side of the midline (total 6 screws in occiput) some institutions prefer bicortical screws but they come at increase risk extend to C2 or lower with polyaxial pedical screws to achieve fixation the safe zone for occipital screws is located within an area measuring 20mm lateral to the external occipital protuberance along the superior nuchal line the major dural venous sinuses are located just below the external occipital protuberance and are at risk of penetrative injury during occipitocervical fusion autogenous bone graft Complications Nonunion Bleeding Internal Carotid Artery Vertebral Artery
QUESTIONS 1 of 2 1 2 Previous Next You have 100% on this question. Just skip this one for now. Take This Question Anyway (OBQ10.200) A 27-year-old female with Down's presents with neck pain, progressive gait instability, and loss of fine motor dexterity in her hands. Flexion and extension radiographs are shown in Figure A and B and demonstrate occipitocervical instability. When performing an occipitocervical fusion, what location in Figure C is most appropriate for placement of an 8mm unicortical screw? Review Topic | Tested Concept QID: 3293 FIGURES: A B C Type & Select Correct Answer 1 A 5% (181/3732) 2 B 53% (1963/3732) 3 C 9% (350/3732) 4 D 18% (678/3732) 5 E 14% (534/3732) L 4 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK
All Videos (1) Podcasts (0) Upgrade to View Premium Videos Upgrade to View Premium Videos Odontoid and Cranio-Cervical Controversies - Dr. Rick C. Sasso Derek Moore Spine - Occipitocervical Instability & Dislocation 12/17/2016 323 views